This blog discusses current weather, weather prediction, climate issues, and other topics

Sunday, June 12, 2011

Scary Snowpack Stories (Updated June 14)

If you believe some of the media, this is what is in store for us, very soon!

They're back--the hyped media claims of serious global warming impacts occurring right now. This week an article in Science magazine on long-term western U.S. snowpack reconstructions using tree rings has set media headlines ablaze across the U.S.:

Researchers See Unusually Rapid Decline in Water Source for Western Rivers (New York Times)"Snowpack in the northern Rocky Mountains has shrunk at an unusually rapid pace during the past 30 years, according to a new study. The decline is "almost unprecedented" over the past 800 years, say researcher"

Study of 800-Year-Old Tree Rings Backs Global Warming (Seattle Times)" The decline in recent decades of the mountain snows that feed the West's major rivers is virtually unprecedented for most of the past millennium..."

Thinning Snows in Rockies Tied to Global Warming (NPR)

What this paper shows is the warming of the 20th century and beyond is already affecting and will profoundly affect the frequency of droughts in the West, simply by whittling away at the snowpack.--Phil Mote, Climate Scientist at Oregon State University.

Rockies Shrinking Snowpack Hurts Water Supply: Changes in Rockies Could Leave Million Without Water(CNN)

"Pederson said the findings add further context to studies that indicate a 30% to 60% decrease in the snows that gather at the upper elevations of the mountains. ... "It's a two-part story," he said. "In a nutshell, what you're seeing is synchronous, declining snowpacks across the West since the 1980s."

I could provide a dozen more of these stories...but you get the message. And when you read these articles, virtually all go on to pin the blame on human-induced global warming. And before I go on, let me make clear that I am not a global warming denier, but a mainstream atmospheric scientist who believes human-induced global warming is inevitable and a major threat if we don't deal with.

So what stimulated all these stories? An article in Science Magazine that was released last week:

The Unusual Nature of Recent Snowpack Declines in the North American Cordillera By Pedersonetal. Here is the abstract:

In western North America, snowpack has declined in recent decades, and further losses are projected through the 21st century. Here, we evaluate the uniqueness of recent declines using snowpack reconstructions from 66 tree-ring chronologies in key runoff-generating areas of the Colorado, Columbia, and Missouri River drainages. Over the past millennium, late-20th-century snowpack reductions are almost unprecedented in magnitude across the northern Rocky Mountains, and in their north-south synchrony across the cordillera. Both the snowpackdeclines and their synchrony result from unparalleled springtime warming due to positive reinforcement of the anthropogenic warming bydecadal variability. The increasing role of warming on large-scale snowpack variability and trends foreshadows fundamental impacts on streamflow and water supplies across the western United States.

In this paper they looked at tree rings around the mountains of the western U.S. (mainly Rockies) and tied their variations to changes in snowpack. Then they show an 800-year chronology of this snowpack and suggest that the recent loss of snowpack is unprecedented in magnitude across the northern Rocky Mountains and the nature of snowpack variations have changed--that snowpack has changed along the entire north-south distance of the Rockies, rather than the north and south being out of phase as they suggest is normal. They further suggest that they in phase loss of snowpack is a sign of general warming: human-caused global warming.

Connecting snowpack variations with a single meteorological value is a tricky business, since trees can respond to variations in temperature, precipitation, insect damage, and human intervention (e.g., thinning or logging), among other things. And problems with tree-ring interpretation was the centerpiece of the recent Hockey-Stick climate controversy and Climategate. But let us accept for the time being that their snowpack-tree ring variation is completely reliable. Should we still accept that scary snowpack tales?

Has there been unusual loss of mountain snowpack the past few decades that suggest rapid human-induced warming? Well, lets go to one of the figures the authors provided in their supplementary information that shows the snowpack (actually snow water equivalent of the snowpack) for the last century for the three areas they talk about--Colorado, Yellowstone and northern Rockies zones. The black lines are based on real measurements of snowpack, the yellow lines are from the tree rings, and the cyan and dark blue lines are smoothed averages of them.

Well, what do we conclude? No real trend in the high upper Colorado Basin and slight downward trends during recent decades (since roughly 1975) from a maximum period in the 50s and 60s. This modulation is consistent with well-known mode of natural variability--the Pacific Decadal Oscillation. And if human-induced global warming is evident it should be after roughly 1970-1980 since before that time our addition of greenhouse gases were too small to have enough impact to be clearly observable.

What about snowpack variations over the nearby Cascades during the past 80 years?A paper published in the peer-reviewed Journal of Climate (I am one of the co-authors) suggests a fairly benign situation:

Since 1976 the snowpack has been INCREASING, and since 1930 the trend is downward by roughly 23%--and much of that could not have been caused by human intervention. As most climatologists know, the earth started to warm after the late 1800s...coming out of the little ice age....and this variation is almost surely natural. Finally, a recently submitted paper by John Christy of U. Alabama, using more snow records than ever before, indicates little loss of snowpack of California during the past century. (see graph)

And here is plot of Snow Water Equivalent (SWE) for Snotel sites from throughout the western U.S. since 1933:

I can show you a lot more snowpack graphs, but the bottom line is that there has NOT been major snowpack losa during the past few decades in the western U.S. and the long-term trend, starting over a hundred years ago, is gently down with some natural variation on top of that.

Here is long-term snowpack graph from the Science article--going back 800 years! (below) Not much change in Colorado. Yellowstone and the northern Rockies are lower recently than most of the historic record, BUT THIS STARTED AROUND 1900 WELL BEFORE THE HUMAN-INDUCED SIGNAL WOULD BE SIGNIFICANT.

The other point of this paper is that the pattern of snowpack change has altered during the past few decades--which they ascribe to anthropogenic global warming. As shown in their figure (below) the northern Rockies and Colorado snowpack tend to be out of phase, which they suggest is due to movement of the jet stream north and south, forced by El Nino and La Nina, for example. The shaded areas indicate what they considerto be anomalous periods where the whole Rockies have less snowpack simultaneously. Now the current period of such anomalous behavior is very short---a very few decades--and that could well be just random noise or natural variability. But just as important, is that there are other periods of similar behavior when global warming could not be the reason. Want to see? Here is an example from the early 20th century (see blue shading)

I hope I haven't bored anyone, but I have spent time on this for a reason. If you really check out the Science paper and look at the data, the loss of snowpack during the past few decades have not been serious. There is no clear smoking gun of anthropogenic global warming.

Folks, we are in the early days of the warming and most of the action is yet to come. We need to be very careful on jumping to conclusions too early, since that only aids the deniers and skeptics who are just looking to pounce on excessive claims.

39 comments:

Coincidentally, several years ago I noticed that for the first time since moving here (1982)the Olympics as seen from Seattle (Mt.Constance, the Brothers, etc.) were about completely devoid of snow in the summer.

So you're saying this occurrence was not unusual and part of the normal cycle. Still, it was unsettling.

Cliff, I appreciate your efforts to correct the record when you see broad conclusions drawn relative to claims of global warming, but your caveats notwithstanding, it seems you only create these posts whenever a claim is made in support of human-induced climate change. I mean, anytime there's a massive snow storm on the East Coast or there happens to be an unusual snow fall on a 13,000-ft. peak in Hawaii in June, the conservative media has a field day taunting Al Gore and human-induced climate change. Here's the latest example from Fox News:

http://twitpic.com/58jrv6

I never read scientists fighting against this kind of thing, maybe because they don't take tabloid media seriously but I think a a majority of Americans do take their cues about what to believe from ledes like the above. I understand your need to correct the record. Indeed, provisionality and skepticism are two of the scientific method's greatest assets, but unfortunately I have no doubt that your snow pack posts will be seen by GW deniers as proof that climate change is a hoax.

It's probably moot at this point--I think the majority of Americans already consider global warming a hoax. You rail against the poor mathematic standards in this state's schools, but that can certainly be extended to a fundamental lack of understanding among the public about the way scientists go about their work.

Thanks for this clear and careful exploration of snowpack and what it might mean in terms of global climate change. I do think global climate change is virtually guaranteed given the way we've pollute the environment, but I bet we're at the beginning of the changes and we might not even recognize them as they start.

I have to admit, I wonder about the rise of huge tornado swarms and more severe tornadoes. Professor Gray is also calling for more, and more, severe hurricanes in the Atlantic. It doesn't take a lot of meteorological knowledge to make you say hmmmmmm....

Please keep exploring these issues. It's VERY interesting, and I really appreciate understanding the thinking behind your opinions on these matters.

Hello Cliff,I am wondering what efforts have been made to estimate or describe the potential cooling impacts of the particulate that was pouring out of all sorts of industrial stacks up to the implementation of the Clean Air Act. Did the particulates from those "not in my backyard" stacks make it up high enough into the atmosphere to effectively reflect sunlight back into space before it became heat and was soaked up by our cozy atmosphere? Furthermore, around the time that the Olympic Games were being held in China I remember seeing pictures showing the amazingly poor air quality (soot so thick that it made my eyes hurt just to look at it). My first question is: Do particulates from ground-level (or smokestack level) sources make it up into the high levels of the atmosphere?Second: If those particulates made it into the upper atmosphere, would they have a cooling effect by virtue of reflecting solar radiation?Third: Is there any record, or way to attempt to quantify the density of those particulates in the upper atmosphere?Fourth: If soot particulates in the upper atmosphere do facilitate cooling, and if they have been present in the atmosphere for the last 60 years (with western nations contributing the bulk of particulates until the 1980's, and China subsequently picking up the slack with its own coal fired plants) should warming estimates be adjusted to account for the soot sheild? Does the snowpack we do have owe a debt of gratitude to this soot? And is it always true that Cold=Snow Pack? Antarctica is cold, but don't portions of it receive precipitation comparable to any desert? I agree that climate is complicated, and for the most part, complexity doesn't sell well.

Cliff,Thanks for your careful analysis. My husband and I are in the ski industry (we operate both Crystal Mountain and the Summit at Snoqualmie). We worry about the decline in snowpack, especially at the Summit, so your words are spiriting. Certainly, the earth's natural warming is being hastened by human influence. But aren't we also trending into a cooling phase? Will that be enough to counter the recent warming?

Thank you for showing that people can be reasonable about global warming and its harms. You can be serious about the problems it will cause without turning into a foaming-at-the-mouth lunatic with every bit of bad news about the environment.

I think part of the problem is people see these things in black-and-white terms - warming either has to be anthropogenic or it must be natural variability. But the real world is rarely black and white, which unfortunately causes issues for folks who can't abide shades of gray.

The onset of the industrial age occurred while the global mean temperature was already climbing (recovery from the "little ice age"); so some post-1850 warming is definitely natural. Recognizing that fact does not make one a "global warming denier" - it simply means one understands that the world's climate is a complicated system.

The Global Warming discussion is a diversion. It takes people away from looking at human unsustainability, population growth, deforestation, ect ect. I don't need graphs or even science at this point to understand change is needed.

I need sciences and engineering at all levels to understand solutions.

I'm actually very interested in global warming because of this. It is almost impossible to figure out if an article is objective or not. So I guess the global warming skeptics and advocates are working together to divert the really important discussions we as a global society should be having.

Given that this blog goes beyond jingoism and soundbites, I'm sorry to see Gary and 1-in-100's posts.

For Gary, I expect Cliff's intention is providing understanding, not presenting only the facts that point one way. How can we move towards an educated public if we self-censor the complexity in science according to our preferred conclusion?

1-in-100 insists that either everything or nothing is warming, and at all times. This misconception may naturally arise from arguments in which the complexity has been hidden from the public.

Paul's question is very good - Science should have required moderation of the conclusion. Painful though it is to complain about politically expedient claims, you should submit a comment to Science. You already have a suite of figures prepared.

Do you have a blog that covers the science of global warming? I would be interested to read such a thing, because nothing that I have gleaned from mainstream media is at all convincing. And Al Gore's movie was a joke: classic case of data garbage-in, garbage-out.

Amen. The problem with the Alarmists is one of magnitude. There has been warming, and there are no doubt human actions that have a multitude of effects. But there is zero crisis. Crisis is entirely dependent on magnitude. If I tell you that ocean levels are rising at 1 mm per year, it is no crisis. You won't live to see any change, and mankind can certainly adapt reasonably to that rise over time. Even if I tell you the oceans rise at 1 mm per day, you've got time to take appropriate action to save all lives and to even save a lot of property. Alarmists are telling us that we need to drastically change our entire economies over very slight changes in climate, and little understood future outcomes. No sensible person buys this nonsense. A question for those who have lived their entire lives in Puget Sound. Can you tell that there has been any appreciable change in sea level at say Alki Beach over you entire life? Enough said.

The extremes of this last year, described in this article, are pretty amazing. Cliff, aren't we just pass a relatively mild multidecade period and now into a not so mild period? This, besides the El Nini/La Nina oscillation could explain all of this.

It will be interesting to see if this is just a bad year, or the new norm. At least it gets everyones' attention.

The question that really needs to be asked is how is the snowpack changing at different altitudes because the average snow level might be rising, but you might get more extreme snow events above that snow level which would lead to a constant or increasing snow pack above the snow level. Once the average snow level gets high enough we will really see the snow pack drop off.

You say not to aid the "skeptics who are just looking to pounce on excessive claims." You are, however, a wonderful example of an intelligent, empirical skeptic (when in scientific inquiry did this become a negative term?!), and you have systematically shredded a set of excessive claims.

You may not consider yourself one of the skeptical. But you are-- (properly) skeptical. One need not be a "denier" to reject the hysteria and authoritarian prescriptions that come with it. Thanks!

Assuming Cliff's analysis is correct, this is just example number X (where X is a very large number) of Science (and Nature) publishing a story that's neat, sexy and probably wrong. The world's two "leading" scientific journals have a peer review process that regularly fails, and the high profile of both journals encourages scientists to submit research that tells a sexy story, sometimes using flawed analysis and cherry-picked data. Sadly, the major media outlets rely disproportionately on these two journals for science news. I'd suggest you submit a rebuttal along the lines of what you've said in your blog, but the acceptance rate of rebuttals is low in both journals. I've often thought about starting a new journal called "Nature and Science Rebuttals" - I suspect it would be overwhelmed with submissions!

While I appreciate your skepticism, I think you are being a little too critical of the authors' conclusions. The long term data (which is the point of looking at tree rings) seems (to me) to indicate that there is a reduction in tree growth in the last 100 years or so. If you feel uncomfortable tying that to anthropogenic warming, that is understandable, but I think you are going too far in trying to deflate the importance of the results.

There are (1) the article's statements, and (2) news reports, including statements by the authors.

The paper is speculative and perhaps overinterpreted but accurate, the reports cross the line, here from Reuters, for example, http://www.reuters.com/article/2011/06/09/us-usa-snowpack-melt-idUSTRE7587B820110609:

The declines can be attributed to unusual springtime warming caused by man-made climate change and come during the summer, which is the period of highest demand for water in the West, it said.

"The more we increase temperature, the earlier we melt out our snow pack and the less of it there is to get though our warm dry summers," said USGS scientist Gregory Pederson, the lead author of the study.

Essentially, this warming is caused by man and will parch late summers in the western US - which seems overreaching for the data in the paper.

Just from a quick perusal, the article claims no precedent for "north-south synchrony", which seems to mean all three regions dipped when anthropogenic influence was strong, compared to similar or even stronger and longer dips from 1900-1950 on just two of the three regions (Fig 1, right frame).

Usually, if a scientist tried to claim 3 out of 3 is significantly more significant than 2 out of 3 given only one sample of each and thresholds selected after the fact, they would be laughed out of the room.

P.S. Cliff, as a subject for a future post, I'd be curious to hear your thoughts on the possibility that our winters are being affected by changes in circulation and conditions in the Arctic, and how (and whether) the AO ties in with that.

Very interesting anaysis. Thank you Cliff. I might add that this June we are still skiing at Crystal Mountain with a 120 inch base at the top. This has been a record year with a season total of 612 inches. Although the current extensive PNW snowpack is likely the result of pdo/la nina 'weather' and not 'climate' I think everyone should take a look at this breaking news from Space.com regarding Solar Cycle 24 and the prospect put forth by the American Astromomical Society that Livingston and Penn may have been correct all along - we may be headed toward a second Maunder Minimum. http://www.space.com/11960-fading-sunspots-slower-solar-activity-solar-cycle.html

Disagree with this blanket statement. However Christy published the CA snowpack paper in Energy & Environment. Only ~ 25 libraries in the entire world subscribe to that, with good reason. E&E doesn't make the ISI list of science journals, which consists of thousands of journals. E&E isn't tallied by the ISI citation index, so practicing scientists would either read nor use it.